WordPress - the popular open source publishing platform - allows you to easily customize your installation with WordPress themes. Installing themes is a simple affair, and if you're just starting out with the publishing application, you can check out this guide on using WordPress themes.

In this collection, you'll find 40 high-quality and free WordPress themes handpicked from the vast amount of free themes out there on the web.

Note: Be sure to check out the license of the theme for restrictions in usage (if any) and it's always good (and very much appreciated) to attribute the designer even if they don't explicitly ask you to.